Control device of vehicle

ABSTRACT

A control device of a vehicle configured to travel on a plurality of travel modes includes an internal combustion engine control unit and a travel mode control unit. When a difference between a rotation speed of an internal combustion at a time when a transition condition is satisfied and a predicted rotation speed is equal to or larger than a threshold value, the internal combustion engine control unit performs rotation speed control such that the rotation speed of the internal combustion engine approaches the predicted rotation speed, and the travel mode control unit shifts a travel mode to a second travel mode after the rotation speed control of the internal combustion engine control unit is completed. The rotation speed control is control in which the rotation speed is changed in a plurality of stages so as to approach the predicted rotation speed.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromprior Japanese patent application No. 2019-230835, filed on Dec. 20,2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a control device of a vehicle.

BACKGROUND ART

In recent years, a hybrid electric vehicle has a plurality of travelmodes including a hybrid travel mode in which in a state where a clutchis disengaged, a generator generates electric power based on power of anengine, an electric motor outputs power at least based on the electricpower supplied by the generator to drive driving wheels; and an enginetravel mode in which the driving wheels are driven by at least poweroutput by the engine in a state where the clutch is engaged (forexample, see WO 2019/003443).

However, in WO 2019/003443, a sudden change in rotation speed of theengine that is not intended by a driver may occur due to a transitionfrom a series travel mode to the engine travel mode. Further, such asudden change in rotation speed of the engine may lead to a reduction inmarketability of the vehicle from a viewpoint of vibration and noise,that is, from a so-called viewpoint of Noise and Vibration (NV).

SUMMARY OF INVENTION

The present invention provides a control device of a vehicle capable ofpreventing a sudden change in rotation speed of an engine while shiftinga travel mode from a first travel mode in which a vehicle travels onpower output by an electric motor in response to supply of electricpower that is generated by a generator based on power of an internalcombustion engine and a second travel mode in which the vehicle travelson the power of the internal combustion engine.

According to the present invention, there is provided a control deviceof a vehicle configured to travel on a plurality of travel modesincluding: a first travel mode in which in response to supply ofelectric power generated by a generator, power output by an electricmotor is transmitted to a driving wheel to drive the vehicle, thegenerator generating the electric power by using power of an internalcombustion engine, and a second travel mode in which power of theinternal combustion engine is transmitted to the driving wheel to drivethe vehicle, the control device comprising: a travel mode control unitconfigured to set, based on a traveling state of the vehicle, any travelmode among the plurality of travel modes as a travel mode in which thevehicle travels; a predicted rotation speed acquisition unit configuredto acquire, when a transition condition to the second travel mode issatisfied based on the traveling state of the vehicle that is travellingin the first travel mode, a predicted rotation speed of the internalcombustion engine when the travel mode is shifted to the second travelmode at a time when the transition condition is satisfied, and aninternal combustion engine control unit that controls the internalcombustion engine, wherein when a difference between a rotation speed ofthe internal combustion at a time when the transition condition issatisfied and the predicted rotation speed acquired by the predictedrotation speed acquisition unit is equal to or larger than a thresholdvalue, the internal combustion engine control unit performs rotationspeed control such that the rotation speed of the internal combustionengine approaches the predicted rotation speed, when the differencebetween the rotation speed of the internal combustion engine and thepredicted rotation speed at a time when the transition condition issatisfied is equal to or larger than the threshold value, the travelmode control unit shifts the travel mode to the second travel mode afterthe rotation speed control of the internal combustion engine controlunit is completed, and the rotation speed control is control in whichthe rotation speed of the internal combustion engine is changed in aplurality of stages so as to approach the predicted rotation speed.

According to the present invention, when the difference between therotation speed of the internal combustion engine at a time when thetransition condition to the second travel mode is satisfied and thepredicted rotation speed of the internal combustion engine when thetravel mode is shafted to the second travel mode at a time when thetransition condition is satisfied is equal to or larger than thethreshold value, the rotation speed control is performed such that therotation speed of the internal combustion engine is changed in aplurality of stages to approach the predicted rotation speed, and thetravel mode is shifted to the second travel mode after the rotationspeed control is completed, so that the travel mode can be shifted tothe second travel mode while preventing the sudden change in rotationspeed of the engine.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a schematic configuration of a vehicleincluding a control device of a vehicle according to an embodiment ofthe present invention.

FIG. 2 is a table showing contents of each travel mode.

FIG. 3 is a graph showing a control example of a rotation speed of anengine in a hybrid travel mode.

FIG. 4 is a block diagram showing a functional configuration of thecontrol device.

FIG. 5 is a graph showing a specific example of rotation speed control.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a control device of a vehicle according to an embodiment ofthe present invention will be described in detail with reference to thedrawings.

First, a vehicle including the control device according to the presentembodiment will be described with reference to FIG. 1. As shown in FIG.1, a vehicle 1 of the present embodiment includes a driving device 10that outputs a driving force of the vehicle 1, and a control device 100that controls the entire vehicle 1 including the driving device 10.

[Driving Device]

As shown in FIG. 1, the driving device 10 includes an engine ENG, agenerator GEN, a motor MOT, a transmission T, and a case 11 thataccommodates the generator GEN, the motor MOT, and the transmission T.The motor MOT and the generator GEN are connected to a battery BATprovided in the vehicle 1, which enables power supply from the batteryBAT and energy regeneration to the battery BAT.

[Transmission]

The case 11 is provided with, along an axial direction in an order froman engine ENG side, a transmission accommodating chamber 11 a foraccommodating the transmission T and a motor accommodating chamber 11 bfor accommodating the motor MOT and the generator GEN.

The transmission accommodating chamber 11 a accommodates an input shaft21, a generator shaft 23, a motor shaft 25, a counter shaft 27 that arearranged in parallel to one another, and a differential mechanism D.

The input shaft 21 is arranged coaxially with and adjacently to acrankshaft 12 of the engine ENG. A driving force of the crankshaft 12 istransmitted to the input shaft 21 via a damper (not shown). The inputshaft 21 is provided with a generator drive gear 32 constituting agenerator gear train Gg.

The input shaft 21 is provided with a low speed-side drive gear 34provided on an engine side with respect to the generator drive gear 32and constituting a low speed-side engine gear train GLo via a firstclutch CL1, and is provided with a high speed-side drive gear 36constituting a high speed-side engine gear train GHi on an opposite sideof the engine side (hereinafter, referred to as a motor side). The firstclutch CL1 is a hydraulic clutch for detachably connecting the inputshaft 21 and the low speed-side drive gear 34, and is a so-calledmulti-plate friction clutch.

The generator shaft 23 is provided with a generator driven gear 40 thatmeshes with the generator drive gear 32. The generator drive gear 32 ofthe input shaft 21 and the generator driven gear 40 of the generatorshaft 23 constitute the generator gear train Gg for transmittingrotation of the input shaft 21 to the generator shaft 23. The generatorGEN is disposed on the motor side of the generator shaft 23. Thegenerator GEN includes a rotor R fixed to the generator shaft 23 and astator S fixed to the case 11 and arranged to face an outer diameterside of the rotor R.

The rotation of the input shaft 21 is transmitted to the generator shaft23 via the generator gear train Gg, and thus the rotor R of thegenerator GEN rotates due to the rotation of the generator shaft 23.Therefore, when the engine ENG is driven, power of the engine ENG inputfrom the input shaft 21 can be converted into electric power by thegenerator GEN.

The motor shaft 25 is provided with a motor drive gear 52 constituting amotor gear train Gm. The motor MOT is disposed on the motor shaft 25closer to the motor side than the motor drive gear 52. The motor MOTincludes a rotor R fixed to the motor shaft 25 and a stator S that isfixed to the case 11 and that is arranged to face an outer diameter sideof the rotor R.

The counter shaft 27 is provided with, in an order from the engine side,a low speed-side driven gear 60 that meshes with the low speed-sidedrive gear 34, an output gear 62 that meshes with a ring gear 70 of thedifferential mechanism D, a high speed-side driven gear 64 that mesheswith the high speed-side drive gear 36 of the input shaft 21 via asecond clutch CL2, and a motor driven gear 66 that meshes with the motordrive gear 52 of the motor shaft 25. The second clutch CL2 is ahydraulic clutch for detachably connecting the counter shaft 27 and thehigh speed-side driven gear 64, and is a so-called multi-plate frictionclutch.

The low speed-side drive gear 34 of the input shaft 21 and the lowspeed-side driven gear 60 of the counter shaft 27 constitute the lowspeed-side engine gear train GLo for transmitting the rotation of theinput shaft 21 to the counter shaft 27. Further, the high speed-sidedrive gear 36 of the input shaft 21 and the high speed-side driven gear64 of the counter shaft 27 constitute the high speed-side engine geartrain GHi for transmitting the rotation of the input shaft 21 to thecounter shaft 27. Here, the low speed-side engine gear train GLoincluding the low speed-side drive gear 34 and the low speed-side drivengear 60 has a reduction ratio higher than that of the high speed-sideengine gear train GHi including the high speed-side drive gear 36 andthe high speed-side driven gear 64.

Therefore, when the first clutch CL1 is engaged and the second clutchCL2 is disengaged at the time of driving the engine ENG, the drivingforce of the engine ENG is transmitted to the counter shaft 27 via thelow speed-side engine gear train GLo at a high reduction ratio.Meanwhile, when the first clutch CL1 is disengaged and the second clutchCL2 is engaged at the time of driving the engine ENG, the driving forceof the engine ENG is transmitted to the counter shaft 27 via the highspeed-side engine gear train GHi at a low reduction ratio. The firstclutch CL1 and the second clutch CL2 are not engaged at the same time.

Further, the motor drive gear 52 of the motor shaft 25 and the motordriven gear 66 of the counter shaft 27 constitute the motor gear trainGm for transmitting the rotation of the motor shaft 25 to the countershaft 27. When the rotor R of the motor MOT is rotated, the rotation ofthe motor shaft 25 is transmitted to the counter shaft 27 via the motorgear train Gm. Thus, when the motor MOT is driven, the driving force ofthe motor MOT is transmitted to the counter shaft 27 via the motor geartrain Gm.

The output gear 62 of the counter shaft 27 and the ring gear 70 of thedifferential mechanism D constitute a final gear train Gf fortransmitting the rotation of the counter shaft 27 to the differentialmechanism D. Therefore, the driving force of the motor MOT that is inputto the counter shaft 27 via the motor gear train Gm, the driving forceof the engine ENG that is input to the counter shaft 27 via the lowspeed-side engine gear train GLo, and the driving force of the engineENG that is input to the counter shaft 27 via the high speed-side enginegear train GHi are transmitted to the differential mechanism D via thefinal gear train Gf and transmitted from the differential mechanism D toan axle DS. Therefore, a driving force for the vehicle 1 to travel isoutput via a pair of driving wheels DW provided at both ends of the axleDS.

The driving device 10 configured as described above has a powertransmission path for transmitting the driving force of the motor MOT tothe axle DS (that is, the driving wheels Dw), a low speed-side powertransmission path for transmitting the driving force of the engine ENGto the axle DS, and a high speed-side power transmission path fortransmitting the driving force of the engine ENG to the axle DS. Thus,as will be described later, the vehicle 1 provided with the drivingdevice 10 can take a plurality of travel modes such as an EV travel modeor a hybrid travel mode in which the vehicle travels on power outputfrom the motor MOT, and a low speed-side engine travel mode or a highspeed-side engine travel mode in which the vehicle travels on poweroutput from the engine ENG.

The control device 100 acquires vehicle information related to thevehicle 1 based on detection signals received from various sensorsprovided in the vehicle 1, and controls the driving device 10 based onthe acquired vehicle information.

Here, the vehicle information includes information indicating atraveling state of the vehicle 1. For example, the vehicle informationincludes, as the information indicating the traveling state of thevehicle 1, information such as a speed of the vehicle 1 (hereinafter,also referred to as a vehicle speed), an accelerator pedal (AP) openingdegree indicating an operation amount (that is, an accelerator position)with respect to an accelerator pedal provided in the vehicle 1, arequired driving force of the vehicle 1 derived based on the vehiclespeed, the AP opening and the like, and the rotation speed of the engineENG (hereinafter referred to as “the engine speed”). The vehicleinformation further includes battery information related to the batteryBAT provided in the vehicle 1. The battery information includes, forexample, information indicating a state of charge (SOC) of the batteryBAT.

The control device 100 controls the driving device 10 based on thevehicle information to drive the vehicle 1 to travel in any of theplurality of travel modes that the vehicle 1 can take. In the control ofthe driving device 10, for example, the control device 100 controls theoutput of power from the engine ENG by controlling the supply of fuel tothe engine ENG, controls the output of power from the motor MOT bycontrolling the supply of electric power to the motor MOT, and controlsthe generation of power (for example, output voltage) of the generatorGEN by controlling a field current or the like flowing through a coil ofthe generator GEN.

Further, in the control of the driving device 10, the control device 100controls the first clutch CL1 to be engaged or disengaged by controllingan actuator (not shown) that operates the first clutch CL1. Similarly,the control device 100 controls the second clutch CL2 to be engaged ordisengaged by controlling an actuator (not shown) that operates thesecond clutch CL2.

In this way, by controlling the engine ENG, the generator GEN, the motorMOT, the first clutch CL1 and the second clutch CL2, the control device100 can drive the vehicle 1 to travel in any of the plurality of travelmodes that the vehicle 1 can take. The control device 100 is an exampleof the control device of a vehicle in the present invention, and forexample, is implemented by an Electronic Control Unit (ECU) including aprocessor, a memory, an interface, and the like.

[Travel Mode that Vehicle can Take]

Next, a travel mode that the vehicle 1 can take will be described withreference to FIG. 2. In FIG. 2, as shown in a travel mode table Ta, thevehicle 1 can take a plurality of travel modes including an EV travelmode, a hybrid travel mode, a low speed-side engine travel mode, and ahigh speed-side engine travel mode.

[EV Travel Mode]

The EV travel mode is a travel mode in which electric power is suppliedto the motor MOT from the battery BAT, and the vehicle 1 travels onpower that is output from the motor MOT according to the electric power.

Specifically, in the EV travel mode, the control device 100 controlsboth the first clutch CL1 and the second clutch CL2 to be disengaged. Inthe EV travel mode, the control device 100 stops injection of fuel tothe engine ENG (so-called fuel cut), and stops output of power from theengine ENG. Then, in the EV travel mode, the control device 100 performscontrol such that electric power is supplied to the motor MOT from thebattery BAT, and power corresponding to the electric power is output tothe motor MOT (shown as Motor: “driven by battery”). As a result, in theEV travel mode, the vehicle 1 travels on power that is output from themotor MOT according the electric power supplied from the battery BAT.

In the EV travel mode, as described above, the output of the power fromthe engine ENG is stopped, and both the first clutch CL1 and the secondclutch CL2 are disengaged. Therefore, in the EV travel mode, no power isinput to the generator GEN, and the generator GEN does not generatepower (shown as Generator: “stop power generation”).

[Hybrid Travel Model]

The hybrid travel mode is an example of a first travel mode of thepresent invention, and is a travel mode in which electric power issupplied to the motor MOT at least from the generator GEN, and thevehicle 1 travels on power that is output from the motor MOT accordingto the electric power.

Specifically, in the hybrid travel mode, the control device 100 controlsboth the first clutch CL1 and the second clutch CL2 to be disengaged.Further, in the hybrid travel mode, the control device 100 performscontrol such that fuel is injected to the engine ENG and power is outputfrom the engine ENG. The power output from the engine ENG is input tothe generator GEN via the generator gear train Gg. As a result, thegenerator GEN generates power.

Then, in the hybrid travel mode, the control device 100 performs controlsuch that the electric power generated by the generator GEN is suppliedto the motor MOT, and power corresponding to the electric power isoutput to the motor MOT (shown as Motor: “driven by generator”). Theelectric power supplied from the generator GEN to the motor MOT islarger than the electric power supplied from the battery BAT to themotor MOT. Therefore, in the hybrid travel mode, the power output fromthe motor MOT (driving force of the motor MOT) can be increased ascompared with that in the EV travel mode, and a large driving force canbe obtained as the driving force of the vehicle 1.

In the hybrid travel mode, the control device 100 may perform controlsuch that the electric power is supplied from the battery BAT to themotor MOT if necessary. That is, in the hybrid travel mode, the controldevice 100 may supply electric power from both the generator GEN and thebattery BAT to the motor MOT. As a result, the electric power suppliedto the motor MOT can be increased as compared to a case where theelectric power is supplied to the motor MOT only from the generator GEN,and a larger driving force can be obtained as the driving force of thevehicle 1.

In addition, in order to provide the driver with a natural feeling inwhich the vehicle speed and the operating sound of the engine ENG are inconjunction with each other even in the hybrid travel mode, as to bedescribed later, the control device 100 controls the engine speed suchthat when the engine speed reaches a predetermined upper limit rotationspeed, the engine speed is temporarily lowered to a predetermined lowerlimit rotation speed and then the engine speed is increased again. Aspecific control example of the engine speed in the hybrid travel modewill be described later with reference to FIG. 3.

[Low Speed-Side Engine Travel Model]

The low speed-side engine travel mode is an example of a second travelmode of the present invention, and is a travel mode in which poweroutput from the engine ENG is transmitted to the driving wheels DW viathe low speed-side power transmission path to drive the vehicle 1.

Specifically, in the low speed-side engine travel mode, the controldevice 100 performs control such that fuel is injected to the engine ENGand power is output from the engine ENG. Further, in the low speed-sideengine travel mode, the control device 100 controls the first clutch CL1to be engaged and controls the second clutch CL2 to be disengaged. Thus,in the low speed-side engine travel mode, the power output from theengine ENG is transmitted to the driving wheels DW via the lowspeed-side engine gear train GLo, the final gear train Gf, and thedifferential mechanism D to drive the vehicle 1.

In the low speed-side engine travel mode, the power output from theengine ENG is also input to the generator GEN via the generator geartrain Gg, but the generator GEN is controlled so as not to generatepower. For example, in the low speed-side engine travel mode, aswitching element (for example, a switching element of an inverterdevice provided between the generator GEN and the battery BAT) providedin an electric power transmission path between the generator GEN and thebattery BAT is turned off, and thus the generator GEN is controlled soas not to generate power. Thus, in the low speed-side engine travelmode, the loss caused by power generation of the generator GEN can bereduced, and an amount of heat generated by the generator GEN or thelike can be reduced. In the low speed-side engine travel mode, duringbraking of the vehicle 1, regenerative power generation may also beperformed by the motor MOT to charge the battery BAT with the generatedelectric power.

In the low speed-side engine travel mode, for example, the controldevice 1X) stops the supply of electric power to the motor MOT, andstops the output of the power from the motor MOT. As a result, in thelow speed-side engine travel mode, the load on the motor MOT can bereduced, and the amount of heat generated by the motor MOT can bereduced.

In the low speed-side engine travel mode, the control device 100 mayperform control such that the electric power is supplied from thebattery BAT to the motor MOT if necessary. Thus, in the low speed-sideengine travel mode, the vehicle 1 can also travel using the power outputfrom the motor MOT based on the electric power supplied from the batteryBAT, and as compared with the case where the vehicle 1 travels on onlythe power of the engine ENG, a larger driving force can be obtained asthe driving force of the vehicle 1.

[High Speed-Side Engine Travel Mode]

The high speed-side engine travel mode is a travel mode in which thepower output from the engine ENG is transmitted to the driving wheels DWvia the high speed-side power transmission path to drive the vehicle 1.

Specifically, in the high speed-side engine travel mode, the controldevice 100 performs control such that fuel is injected to the engine ENGand power is output from the engine ENG. Further, in the high speed-sideengine travel mode, the control device 100 controls the second clutchCL2 to be engaged, and controls the first clutch CL1 to be disengaged.Thus, in the high speed-side engine travel mode, the power output fromthe engine ENG is transmitted to the driving wheels DW via the highspeed-side engine gear train GHi, the final gear train Gf, and thedifferential mechanism D to drive the vehicle 1.

In the high speed-side engine travel mode, the power output from theengine ENG is also input to the generator GEN via the generator geartrain Gg, but the generator GEN is controlled so as not to generatepower. As a result, in the high speed-side engine travel mode, the losscaused by the power generation of the generator GEN can be reduced, andthe amount of heat generated by the generator GEN or the like can bereduced. In the high speed-side engine travel mode, during braking ofthe vehicle 1, regenerative power generation may also be performed bythe motor MOT to charge the battery BAT with the generated electricpower.

In the high speed-side engine travel mode, for example, the controldevice 100 stops the supply of electric power to the motor MOT, andstops the output of the power from the motor MOT. As a result, in thehigh speed-side engine travel mode, the load on the motor MOT can bereduced, and the amount of heat generated by the motor MOT can bereduced.

In the high speed-side engine travel mode, the control device 100 maysupply the electric power from the battery BAT to the motor MOT ifnecessary. Thus, in the high speed-side engine travel mode, the vehicle1 can also travel using the power output from the motor MOT based on theelectric power supplied from the battery BAT, and as compared with thecase where the vehicle 1 travels on only the power of the engine ENG, alarger driving force can be obtained as the driving force of the vehicle1.

[Engine Speed in Hybrid Travel Model]

Next, a control example of the engine speed in the hybrid travel modewill be described with reference to FIG. 3. In FIG. 3, a vertical axisshows the engine speed [rpm], and a horizontal axis shows a vehiclespeed [km/h].

The engine speed Ne1 shown in FIG. 3 is an engine speed in the hybridtravel mode. As shown in the engine speed Ne1, in the hybrid travelmode, the control device 100 controls, for example, by an engine controlunit 131 to be described later, the engine speed so as to fluctuatebetween an upper limit rotation speed NeH and a lower limit rotationspeed NeL that are predetermined.

Specifically, in the hybrid travel mode, the control device 100 firstincreases the engine speed, as the vehicle speed increases, at apredetermined increase rate a1 from a state where both the vehicle speedand the engine speed are 0 (zero). Then, when the engine speed reachesan upper limit rotation speed NeH corresponding to the vehicle speed atthat time, the engine speed is reduced to a lower limit rotation speedNeL corresponding to the vehicle speed at that time. Thereafter, thecontrol device 100 increases the engine speed from the lower limitrotation speed NeL as the vehicle speed increases again. However, atthis time, the engine speed is increased at an increase rate a2 smallerthan the increase rate a1.

In the same way thereafter, when the engine speed reaches the upperlimit rotation speed NeH, the control device 100 reduces the enginespeed to the lower limit rotation speed NeL, and as the vehicle speedincreases, increases the engine speed while changing the increase rateto an increase rate a3 an increase rate a4, and an increase rate a5 eachtime. Here, the increase rate a2>the increase rate a3>the increase ratea4>the increase rate a5.

In the hybrid travel mode, since both the first clutch CL1 and thesecond clutch CL2 are disengaged as described above, the engine speedcan be set freely regardless of the vehicle speed. However, bycontrolling the engine speed so as to fluctuate between the upper limitrotation speed NeH and the lower limit rotation speed NeL as the vehiclespeed increases, the driver can feel a natural change in operating soundof the engine ENG in conjunction with the vehicle speed as if the gearis shifted by a stepped transmission even the vehicle 1 is travelling inthe hybrid travel mode.

Further, an engine speed Ne2 shown in FIG. 3 is an engine speed in thelow speed-side engine travel mode. As described above, in the lowspeed-side engine travel mode, the engine ENG and the axle DS (that is,the driving wheels DW) are mechanically connected. Therefore, asindicated by the engine speed Ne2, the engine speed and the vehiclespeed linearly correspond to each other. Specifically, in the presentembodiment, in the low speed-side engine travel mode, the engine speedincreases at an increase rate a11 as the vehicle speed increases. Forexample, here, the increase rate a2>the increase rate a11>the increaserate a3.

Further, an engine speed Ne3 shown in FIG. 3 is an engine speed in thehigh speed-side engine travel mode. As described above, in the highspeed-side engine travel mode, the engine ENG and the axle DS aremechanically connected in the same manner as in the low speed-sideengine travel mode. Therefore, as indicated by the engine speed Ne3, theengine speed and the vehicle speed linearly correspond to each other.Specifically, in the present embodiment, in the high speed-side enginetravel mode, the engine speed increases at an increase rate a12 as thevehicle speed increases. For example, here, the increase rate a4>theincrease rate a12>the increase rate a5.

Although the engine speed Ne2 and the engine speed Ne3 in a state wherethe vehicle speed is 0 (zero) are illustrated in FIG. 3 for easyunderstanding, the low speed-side engine travel mode or the highspeed-side engine travel mode may not be actually set when the vehiclespeed is 0 (zero).

[Functional Configuration of Control Device]

Next, a functional configuration of the control device 100 will bedescribed with reference to FIG. 4. As shown in FIG. 4, the controldevice 100 includes a vehicle information acquisition unit 110 thatacquires the vehicle information, a travel mode control unit 120 thatcontrols a travel mode in the vehicle 1, and a driving device controlunit 130 that controls the driving device 10.

For example, the vehicle information acquisition unit 110, the travelmode control unit 120, and the driving device control unit 130 canrealize the functions thereof by executing programs stored in a memoryby a processor of the ECU that implements the control device 100, or byan interface of the ECU.

The vehicle information acquisition unit 110 acquires vehicleinformation based on detection signals and the like sent from varioussensors provided in the vehicle 1 to the control device 100, andtransmits the acquired vehicle information to the travel mode controlunit 120 and the driving device control unit 130. As described above,the vehicle information includes information indicating the travelingstate of the vehicle 1 such as the vehicle speed, the AP opening degree,and the engine speed. Thus, the vehicle information acquisition unit 110can notify the travel mode control unit 120 and the driving devicecontrol unit 130 of the traveling state of the vehicle 1.

For example, the vehicle speed can be acquired based on a detectionsignal from a vehicle speed sensor S1 that detects a rotation speed ofthe axle DS. The AP opening degree can be acquired based on a detectionsignal from an accelerator position sensor (AP sensor) S2 that detectsan operation amount with respect to the accelerator pedal provided inthe vehicle 1. The engine speed can be acquired based on a detectionsignal from an engine speed sensor (ENG speed sensor) S3 that detectsthe engine speed. Further, the vehicle information acquisition unit 110may acquire vehicle information including information indicating therequired driving force of the vehicle 1 that was derived based on thevehicle speed, the AP opening degree, and the like.

The vehicle information further includes battery information. Thebattery information includes information indicating the SOC of thebattery BAT. Specifically, the vehicle 1 includes a battery sensor S4that detects an inter-terminal voltage or charge/discharge current ofthe battery BAT, a temperature of the battery BAT, and the like. Thebattery sensor S4 sends the detected signals to the control device 100.The vehicle information acquisition unit 110 acquires batteryinformation including information indicating the SOC of the battery BATthat is derived based on the inter-terminal voltage, thecharge/discharge current, the temperature, and the like of the batteryBAT that are detected by the battery sensor S4. The battery informationmay include information indicating the inter-terminal voltage, thecharge/discharge current, the temperature, and the like of the batteryBAT That are detected by the battery sensor S4.

The travel mode control unit 120 includes a travel mode setting unit121, and a predicted rotation speed acquisition unit 122. Based on thetraveling state of the vehicle 1, the travel mode setting unit 121 setsany travel mode among the plurality of travel modes as the travel modein which the vehicle 1 travels.

Specifically, the control device 100 stores, in advance, informationindicating a transition condition that is a condition for transition toeach of the travel modes. The information indicating the transitioncondition is configured such that information indicating, for example, apre-transition travel mode (for example, the hybrid travel mode), atransition destination travel mode (for example, the low speed-sideengine travel mode), and a traveling state of the vehicle 1 (forexample, the vehicle speed and the driving force of vehicle 1) which isa transition condition from the pre-transition travel mode to thetransition destination travel mode are associated with one another. Thetravel mode setting unit 121 sets the travel mode in which the vehicle 1travels by referring to the current travel mode of the vehicle 1, thetraveling state of the vehicle 1 indicated by the vehicle information,and the information indicating the transition condition.

For example, it is assumed that the traveling state of the vehicle 1that is travelling in the hybrid travel mode is changed so as to matchthe traveling state of the vehicle 1 which is the transition conditionfrom the hybrid travel mode to the low speed-side engine travel mode. Inthis case, the traveling mode setting unit 121 shifts the travel mode ofthe vehicle 1 from the hybrid travel mode to the low speed-side enginetravel mode on the assumption that the transition condition from thehybrid travel mode to the low speed-side engine travel mode issatisfied. Specifically, in this case, the travel mode setting unit 121shifts the travel mode from the hybrid travel mode to the low speed-sideengine travel mode by the driving device control unit 130 controllingthe first clutch CL1 to be engaged.

Hereinafter, the transition condition from the hybrid travel mode to thelow speed-side engine travel mode is also simply referred to as“transition condition to the low speed-side engine travel mode”.Hereinafter, the transition from the hybrid travel mode to the lowspeed-side engine travel mode is also simply referred to as “transitionto the low speed-side engine travel mode”.

For example, a travel mode operation switch (not shown) that can beoperated by the driver may be provided in the vehicle 1, and the travelmode setting unit 121 may set the travel mode by referring to presenceor absence of operation on the travel mode operation switch. Forexample, if there is an operation on the travel mode operation switch,the travel mode setting unit 121 may shift the travel mode to the lowspeed-side engine travel mode on the assumption that the transitioncondition to the low speed-side engine travel mode is satisfied. Forexample, if there is an operation on the travel mode operation switchand the traveling state of the vehicle 1 is suitable for travelling inthe low speed-side engine travel mode, the travel mode setting unit 121may shift the travel mode to the low speed-side engine travel mode onthe assumption that the transition condition to the low speed-sideengine travel mode is satisfied.

As described above, in the hybrid travel mode in which the axle DS (thatis, the driving wheels DW) and the engine ENG are not mechanicallyconnected and the engine speed fluctuates between the upper limitrotation speed NeH and the lower limit rotation speed NeL, the enginespeed may be the upper limit rotation speed NeH even if the vehiclespeed is in a low speed range, or the engine speed may be the lowerlimit rotation speed NeL even if the vehicle speed is in a high speedrange.

Meanwhile, in the low speed-side engine travel mode in which the axle DSand the engine ENG are mechanically connected, the engine speed and thevehicle speed linearly correspond to each other. That is, in the lowspeed-side engine travel mode, since the engine speed increasesmonotonously as the vehicle speed increases, the engine ENG does notrotate at high speed when the vehicle speed is in the low speed range,and the engine ENG does not rotate at low speed when the vehicle speedis in the high speed range.

Due to such a difference in engine speed characteristics between thehybrid travel mode and the low speed-side engine travel mode, when thetransition to the low speed-side engine travel mode is performed at atime when the transition condition to the low speed-side engine travelmode is satisfied, there is a possibility that a sudden change in enginespeed that is not intended by the driver (for example, even though thedriver is performing a certain operation on the accelerator pedal) mayoccur along with the transition. Such a sudden change in engine speedmay lead to a reduction in marketability of the vehicle 1 from theviewpoint of NV.

Therefore, when it is predicted that a sudden change in engine speed mayoccur due to the transition to the low speed-side engine travel mode,the travel mode setting unit 121 shifts the travel mode to the lowspeed-side engine travel mode after the situation where such a suddenchange in engine speed does not occur.

Specifically, when the transition condition to the low speed-side enginetravel mode is satisfied based on the traveling state of the vehicle 1that is travelling in the hybrid travel mode, the predicted rotationspeed acquisition unit 122 provided in the travel mode control unit 120acquires a predicted rotation speed which is a predicted value of theengine speed when the travel mode is shifted to the low speed-sideengine travel mode at a time when the transition condition is satisfied.

For example, the control device 100 stores in advance correspondenceinformation indicating a correspondence relationship between the vehiclespeed and the engine speed in the low speed-side engine travel mode. Thepredicted rotation speed acquisition unit 122 acquires, as the predictedrotation speed, an engine speed corresponding to the vehicle speedindicated by the vehicle information by referring to the correspondenceinformation.

For example, it is assumed that the vehicle speed at a time when thetransition condition to the low speed-side engine travel mode issatisfied is vX. Further, it is assumed that in the correspondenceinformation, the engine speed corresponding to the vehicle speed vX isNeX. In this case, the predicted rotation speed acquisition unit 122acquires the NeX corresponding to the vX in the correspondenceinformation as the predicted rotation speed when the travel mode isshifted to the low speed-side engine travel mode at a time when thetransition condition to the low speed-side engine travel mode issatisfied.

Then, the travel mode setting unit 121 determines whether a differencebetween the engine speed at a time when the transition condition to thelow speed-side engine travel mode is satisfied and the predictedrotation speed when the travel mode is shifted to the low speed-sideengine travel mode at a time when the transition condition is satisfiedis equal to or larger than a threshold value. This threshold value ispredetermined and stored in the control device 100. For example, thethreshold value is larger than an upper limit value of a fluctuationrange of the engine speed allowed from the viewpoint of NV (hereinafter,also referred to as “allowable upper limit value”).

If the difference between the engine speed at a time when the transitioncondition to the low speed-side engine travel mode is satisfied and thepredicted rotation speed when the travel mode is shifted to the lowspeed-side engine travel mode at a time when the transition condition issatisfied is equal to or larger than the threshold value, the travelmode setting unit 121 notifies the driving device control unit 130 ofthe determination result, and reserves the transition to the lowspeed-side engine travel mode until to-be-described rotation speedcontrol performed by the driving device control unit 130 (engine controlunit 131) is completed.

For example, it is assumed that the vehicle speed is vX and the enginespeed is NeY at a time when the transition condition to the lowspeed-side engine travel mode is satisfied. In this case, as describedabove, the NeX is acquired as the predicted rotation speed. Therefore,the travel mode setting unit 121 determines whether the differencebetween the NeY which is the engine speed at a time when the transitioncondition to the low speed-side engine travel mode is satisfied and NeXwhich is the predicted rotation speed when the travel mode is shifted tothe low speed-side engine travel mode at a time when the transitioncondition is satisfied is equal to or greater than the threshold value.

That is, here, when the threshold value is set to Th, the travel modesetting unit 121 determines whether |NeY−NeX|≥Th. Then, if |NeY−NeX|≥Th,the travel mode setting unit 121 notifies the driving device controlunit 130 of the determination result, and reserves the transition to thelow speed-side engine travel mode until the rotation speed control to bedescribed later is completed. Therefore, in a situation where it ispredicted that the sudden change in engine speed may occur due to thetransition to the low speed-side engine travel mode, the travel modesetting unit 121 can prevent the transition to the low speed-side enginetravel mode.

The travel mode setting unit 121 shifts the travel mode to the lowspeed-side engine travel mode directly if the difference between theengine speed at a time when the transition condition to the lowspeed-side engine travel mode is satisfied and the predicted rotationspeed when the travel mode is shifted to the low speed-side enginetravel mode at a time when the transition condition is satisfied issmaller than the threshold value. That is, in this case, the transitionto the low speed-side engine travel mode is performed at a time when thetransition condition to the low speed-side engine travel mode issatisfied without reservation. Therefore, in a situation where it ispredicted that the sudden change in engine speed will not occur due tothat the transition to the low speed-side engine travel mode isperformed, the travel mode can be quickly shifted to the low speed-sideengine travel mode corresponding to the traveling state of the vehicle 1and the vehicle 1 can travel efficiently.

The driving device control unit 130 controls the driving device 10 basedon the travel mode set by the travel mode control unit 120 (the travelmode setting unit 121), the vehicle information acquired by the vehicleinformation acquisition unit 110, and the like. Specifically, thedriving device control unit 130 includes the engine control unit 131that controls the engine ENG, a first clutch control unit 132 thatcontrols the first clutch CL1, and a second clutch control unit 133 thatcontrols the second clutch CL2.

For example, in the low speed-side engine travel mode or the highspeed-side engine travel mode, the engine control unit 131 controls theengine ENG to output a driving force that realizes the required drivingforce indicated by the vehicle information to the engine ENG. In thehybrid travel mode, the engine control unit 131 controls the engine ENG(that is, power generation of the generator in this case) to output adriving force that realizes the required driving force indicated by thevehicle information to the motor MOT. Further, in the hybrid travelmode, the engine control unit 131 controls the engine speed to fluctuatebetween the predetermined upper limit rotation speed NeH and lower limitrotation speed NeL as described above.

The first clutch control unit 132 controls engagement and disengagementof the first clutch CL1 according to the travel mode set by the travelmode control unit 120 (the travel mode setting unit 121). Specifically,as described above, the first clutch control unit 132 controls the firstclutch CL1 to be engaged when the low speed-side engine travel mode isset, and controls the first clutch CL1 to be disengaged when anothertravel mode is set.

Similarly to the first clutch control unit 132, the second clutchcontrol unit 133 also controls the engagement and disengagement of thesecond clutch CL2 according to the travel mode set by the travel modecontrol unit 120. Specifically, as described above, the second clutchcontrol unit 133 controls the second clutch CL2 to be engaged when thehigh speed-side engine travel mode is set, and controls the secondclutch CL2 to be disengaged when another travel mode is set.

When receiving, from the travel mode control unit 120 (travel modesetting unit 121), the determination result that the difference betweenthe engine speed at a time when the transition condition to the lowspeed-side engine travel mode is satisfied and the predicted rotationspeed when the travel mode is shifted to the low speed-side enginetravel mode at a time when the transition condition is satisfied isequal to or larger than the threshold value, the engine control unit 131performs predetermined rotation speed control.

The rotation speed control is control in which the engine speed ischanged in a plurality of stages so as to approach the predictedrotation speed. For example, the rotation speed control is control inwhich the engine speed approaches the predicted rotation speed by achange of the allowable upper limit value in a first stage, and theengine speed gradually approaches the predicted speed at a predeterminedrate of change in a second and subsequent stages. A specific example ofthe rotation speed control will be described later with reference toFIG. 5.

For example, in a case where the engine control unit 131 performs therotation speed control, when the rotation speed control is completed,the engine control unit 131 notifies the travel mode control unit 120(travel mode setting unit 121) of the completion. Then, in response tothe reception of the notification, the travel mode setting unit 121engages the first clutch CL1 and shifts the travel mode to the reservedlow speed-side engine travel mode.

[Specific Example of Rotation Speed Control]

Next, a specific example of the rotation speed control will be describedwith reference to FIG. 5. In FIG. 5, a vertical axis shows the enginespeed [rpm] and a horizontal axis shows the time t.

At a time point t1 in FIG. 5, it is assumed that the vehicle 1 istravelling in the hybrid travel mode, and the transition condition tothe low speed-side engine travel mode is satisfied. Further, it isassumed that the engine speed at that time is Nel1 [rpm], the predictedrotation speed acquired based on the vehicle speed at that time is Nel2[rpm](Nel2<Nel1), and a difference between the Nel1 [rpm] and Nel2 [rpm]is equal to or larger than the threshold value (that is,|Nel1−Nel2|≥Th). In this case, the control device 100 performs therotation speed control by the engine control unit 131

Specifically, in the rotation speed control in this case, the controldevice 100 first lowers the engine speed from Nel1 [rpm] by Ne20 [rpm]which is the allowable upper limit value. As a result, the engine speedis set to Nel3 [rpm] at a time point t2 immediately after the time pointt1. Here, Nel3 [rpm]=Nel1 [rpm]−Ne20 [rpm]. Ne20 [rpm] may be apredetermined constant value or a value derived from Nel1 [rpm] (forexample, Ne20 [rpm]=Nel1 [rpm]×predetermined ratio).

Next, the control device 100 lowers the engine speed from Nel3 [rpm] ata constant rate of change R1 until the engine speed reaches Nel2 [rpm].Here, the rate of change R1 is, for example, a rate of change by whichthe engine speed is lowered by several tens [rpm] per second. The rateof change R1 is not limited to this example, and may be appropriatelydetermined by, for example, a manufacturer of the vehicle 1. Further,the rate of change R1 is not limited to a predetermined constant value,and may be, for example, a variable value that increases as thedifference between Nel3 [rpm] and Nel2 [rpm] increases. By setting therate of change R1 to such a variable value, the time required by therotation speed control can be shortened.

Then, when the engine speed reaches Nel2 [rpm], the control device 100shifts the travel mode to the low speed-side engine travel mode.Specifically, when the engine speed reaches Nel2 [rpm], the controldevice 100 shifts the travel mode to the low speed-side engine travelmode by engaging the first clutch CL1.

The two-stage rotation speed control in which the engine speed is firstlowered by Ne20 [rpm] which is the allowable upper limit value, and thenis lowered gradually in the rate of change R1 is described here, but thepresent invention is not limited thereto. For example, the rotationspeed control may be one including three stages in which the enginespeed is first lowered by Ne20 [rpm] which is the allowable upper limitvalue, thereafter is lowered in the rate of change R1, and then islowered in a rate of change R2 (for example, the rate of change R2<therate of change R1). Further, the rotation speed control may be performedin multiple stages rather than three stages. However, it is preferablethat the amount of change in engine speed per unit time decreases as therotation speed control reaches a later stage in chronological order.

Further, the rotation speed control of lowering the engine speed isdescribed here, but the control device 100 may perform rotation speedcontrol of increasing the engine speed, for example, in a case where theengine speed is to be increased due to transition to the low speed-sideengine travel mode.

Specifically, for example, it is assumed that the transition conditionto the low speed-side engine travel mode is satisfied at a certain timepoint while the vehicle 1 is traveling in the hybrid travel mode.Further, it is assumed that the engine speed at that time is Nel1 [rpm],the predicted rotation speed acquired based on the vehicle speed at thattime is Nel4 [rpm] (Nel4>Nel1), and a difference between the Nel1 [rpm]and Nel4 [rpm] is equal to or larger than the threshold value (that is,|Nel1−Nel4|≥Th).

In the rotation speed control in this case, the control device 100 firstincreases the engine speed by Ne20 [rpm] which is the allowable upperlimit value, and the engine speed reaches Nel5 [rpm]. Here, Nel5[rpm]=Nel1 [rpm]+Ne20 [rpm]. Next, the control device 100 increases theengine speed from Nel5 [rpm] at a predetermined rate of change until theengine speed reaches Nel4 [rpm], and shifts the travel mode to the lowspeed-side engine travel mode when the engine speed reaches Ne14 [rpm].As described above, even in a case of increasing the engine speed due totransition to the low speed-side engine travel mode, the control device100 can shift the travel mode to the low speed-side engine travel modewhile preventing the sudden change in engine speed.

As described above, when it is predicted that a sudden change in enginespeed may occur due to the transition to the low speed-side enginetravel mode, the control device 100 shifts the travel mode to the lowspeed-side engine travel mode while performing the rotation speedcontrol such that the engine speed is changed in a plurality of stagesby the rotation speed control so as to approach the predicted rotationspeed. Accordingly, the control device 100 can shift the travel mode tothe low speed-side engine travel mode corresponding to the travelingstate of the vehicle 1 while preventing the sudden change in enginespeed, and the vehicle 1 can travel efficiently.

Further, since the control device 100 changes the engine speed by onlythe allowable upper limit value to approach the predicted rotation speedin the first stage of the rotation speed control, the engine speed canquickly approaches the predicted rotation speed within a predeterminedallowable range. Then, since the control device 100 changes the enginespeed in a predetermined rate of change to gradually approach thepredicted rotation speed in the second stage and subsequent stages ofthe rotation speed control, the engine speed can approach the predictedrotation speed without giving the driver a sense of discomfort.

An embodiment of the present invention has been described above, but thepresent invention is not limited to the above embodiment, and can beappropriately modified, improved, or the like. For example, an examplein which the travel mode is shifted from the hybrid travel mode to thelow speed-side engine travel mode has been described in the aboveembodiment, but it is conceivable a possibility that a sudden change inengine speed may also occur in a case where the travel mode is shiftedfrom the hybrid travel mode to the high speed-side engine travel mode.Therefore, the control device 100 may perform the rotation speed controleven when the transition condition from the hybrid travel mode to thehigh speed-side engine travel mode is satisfied.

Specifically, correspondence information indicating a correspondencerelationship between a vehicle speed and an engine speed in the highspeed-side engine travel mode is stored in advance in the control device100, so that the control device 100 can acquire, by referring to thecorrespondence information, the predicted rotation speed when the travelmode is shifted to the high speed-side engine travel mode. Then, thecontrol device 100 may perform the rotation speed control when adifference between the engine speed and the predicted rotation speed ata time when the transition condition to the high speed-side enginetravel mode is satisfied is equal to or larger than the threshold value.

Similarly, it is conceivable a possibility that a sudden change inengine speed may also occur due to the transition from the lowspeed-side engine travel mode to the high speed-side engine travel modeor the transition from the high speed-side engine travel mode to the lowspeed-side engine travel mode. Therefore, when the transition conditionfrom the low speed-side engine travel mode to the high speed-side enginetravel mode or the transition condition from the high speed-side enginetravel mode to the low speed-side engine travel mode is satisfied, thecontrol device 100 may also perform the rotation speed control similarlyto the above example.

The present specification describes at least the following matters. Thecomponents and the like corresponding to the above-described embodimentsare shown in parentheses, but the present invention is not limitedthereto.

(1) A control device (control device 100) of a vehicle (vehicle 1)configured to travel on a plurality of travel modes including:

a first travel mode (hybrid travel mode) in which in response to supplyof electric power generated by a generator (generator GEN), power outputby an electric motor (motor MOT) is transmitted to a driving wheel(driving wheel DW) to drive the vehicle, the generator generating theelectric power by using power of an internal combustion engine (engineENG), and

a second travel mode (low speed-side engine travel mode) in which powerof the internal combustion engine is transmitted to the driving wheel todrive the vehicle, the control device comprising:

a travel mode control unit (travel mode control unit 120) configured toset, based on a traveling state of the vehicle, any travel mode amongthe plurality of travel modes as a travel mode in which the vehicletravels; and

a predicted rotation speed acquisition unit (predicted rotation speedacquisition unit 122) configured to acquire, when a transition conditionto the second travel mode is satisfied based on the traveling state ofthe vehicle that is travelling in the first travel mode, a predictedrotation speed of the internal combustion engine when the travel mode isshifted to the second travel mode at a time when the transitioncondition is satisfied,

an internal combustion engine control unit (engine control unit 131)that controls the internal combustion engine, wherein

when a difference between a rotation speed (Nel1) of the internalcombustion engine at a time when the transition condition is satisfiedand the predicted rotation speed (Nel2) acquired by the predictedrotation speed acquisition unit is equal to or larger than a thresholdvalue, the internal combustion engine control unit performs rotationspeed control such that the rotation speed of the internal combustionengine approaches the predicted rotation speed,

when the difference between the rotation speed of the internalcombustion engine and the predicted rotation speed at a time when thetransition condition is satisfied is equal to or larger than thethreshold value, the travel mode control unit shifts the travel mode tothe second travel mode after the rotation speed control of the internalcombustion engine control unit is completed, and

the rotation speed control is control in which the rotation speed of theinternal combustion engine is changed in a plurality of stages so as toapproach the predicted rotation speed.

According to the above (1), when the difference between the rotationspeed of the internal combustion engine at a time when the transitioncondition to the second travel mode is satisfied and the predictedrotation speed of the internal combustion engine when the travel mode isshifted to the second travel mode at a time when the transitioncondition is satisfied is equal to or larger than the threshold value,the rotation speed control is performed such that the rotation speed ofthe internal combustion engine is changed in a plurality of stages toapproach the predicted rotation speed, and the travel mode is shifted tothe second travel mode after the rotation speed control is completed, sothat the travel mode can be shifted to the second travel mode whilepreventing the sudden change in rotation speed of the engine.

(2) In the control device of a vehicle according the above (1), therotation speed control is control in which in a first stage among theplurality of stages, the rotation speed of the internal combustionengine is changed by only an allowable upper limit value to approach thepredicted rotation speed.

According to the above (2), since the rotation speed control is controlin which in the first stage, the rotation speed of the internalcombustion engine is changed by only an allowable upper limit value toapproach the predicted rotation speed, the rotation speed of theinternal combustion engine can quickly approach the predicted rotationspeed within a predetermined allowable range.

(3) In the control device of a vehicle according to the above (2), therotation speed control is control in which in a second stage andsubsequent stages among the plurality of stages, the rotation speed ofthe internal combustion engine is changed in a predetermined rate ofchange to gradually approach the predicted rotation speed.

According to the above (3), since the rotation speed control is controlin which in the second stage and the subsequent stages, the rotationspeed of the internal combustion engine is changed in a predeterminedrate of change to gradually approach the predicted rotation speed, therotation speed of the internal combustion engine can approach thepredicted rotation speed without giving the driver a sense ofdiscomfort.

What is claimed is:
 1. A control device of a vehicle configured totravel on a plurality of travel modes including: a first travel mode inwhich in response to supply of electric power generated by a generator,power output by an electric motor is transmitted to a driving wheel todrive the vehicle, the generator generating the electric power by usingpower of an internal combustion engine, and a second travel mode inwhich power of the internal combustion engine is transmitted to thedriving wheel to drive the vehicle, the control device comprising: atravel mode control unit configured to set, based on a traveling stateof the vehicle, any travel mode among the plurality of travel modes as atravel mode in which the vehicle travels; a predicted rotation speedacquisition unit configured to acquire, when a transition condition tothe second travel mode is satisfied based on the traveling state of thevehicle that is travelling in the first travel mode, a predictedrotation speed of the internal combustion engine when the travel mode isshifted to the second travel mode at a time when the transitioncondition is satisfied, and an internal combustion engine control unitthat controls the internal combustion engine, wherein when a differencebetween a rotation speed of the internal combustion at a time when thetransition condition is satisfied and the predicted rotation speedacquired by the predicted rotation speed acquisition unit is equal to orlarger than a threshold value, the internal combustion engine controlunit performs rotation speed control such that the rotation speed of theinternal combustion engine approaches the predicted rotation speed, whenthe difference between the rotation speed of the internal combustionengine and the predicted rotation speed at a time when the transitioncondition is satisfied is equal to or larger than the threshold value,the travel mode control unit shifts the travel mode to the second travelmode after the rotation speed control of the internal combustion enginecontrol unit is completed, and the rotation speed control is control inwhich the rotation speed of the internal combustion engine is changed ina plurality of stages so as to approach the predicted rotation speed. 2.The control device of a vehicle according to claim 1, wherein therotation speed control is control in which in a first stage among theplurality of stages, the rotation speed of the internal combustionengine is changed by only an allowable upper limit value to approach thepredicted rotation speed.
 3. The control device of a vehicle accordingto claim 2, wherein the rotation speed control is control in which in asecond stage and subsequent stages among the plurality of stages, therotation speed of the internal combustion engine is changed in apredetermined rate of change to gradually approach the predictedrotation speed.